Linear lighting is a particular class of solid-state lighting that uses light-emitting diodes (LED). In this type of lighting, a long, narrow printed circuit board (PCB) is populated with LED light engines, usually spaced at a regular pitch or spacing. The PCB may be either rigid or flexible, and other circuit components may be included on the PCB, if necessary. Depending on the type of LED light engine or engines that are used, the linear lighting may emit a single color, or may be capable of emitting multiple colors.
In combination with an appropriate power supply or driver, linear lighting is considered to be a luminaire in its own right, and it is also used as a raw material for the production of more complex luminaires, such as light-guide panels. In practice, strips of PCB may be joined together in the manufacturing process to produce linear lighting of essentially any length. Spools of linear lighting 30 meters (98 ft) in length are common, and spools of linear lighting 100 meters (328 ft) in length are commercially available.
Fundamentally, linear lighting is a microelectronic circuit. That circuit is susceptible to physical damage. Therefore, manufacturers have sought ways to make linear lighting more robust and more resistant to damage from physical impact and ingress of water and other debris. One of the most popular ways to protect linear lighting is to encapsulate it—i.e., to encase it—within a polymer resin. Two popular types of polymer resins used to encapsulate linear lighting are polyurethanes and silicones. Depending on the application and the polymer, the encapsulation itself may be rigid or flexible.
In a typical process, a polymeric channel is first manufactured, usually by casting it from a liquid resin or extruding it. The linear lighting is installed in that channel, and the channel is then filled with resin to complete the encapsulation process. The polymer resin typically has a low viscosity when it is first dispensed, and so the channel in which the linear lighting is placed must be capped or dammed in order to prevent the polymer resin from leaking out. This is easier if the encapsulated linear lighting is made only to specific lengths, in which case dammed channels of those specific lengths can be made. If linear lighting of arbitrary length is needed, the typical solution is to glue a cast or injection-molded endcap into the channel at an appropriate point. While this is effective, it is also time-consuming, and because it uses adhesive and a cap that may be made of a different material, it may introduce undesirable compounds into the encapsulation. Better ways of preventing leaks in linear lighting encapsulation processes would be helpful.